/Engine/Plugins/Developer/Concert/ConcertSync/ConcertSyncCore/Source/ConcertSyncCore/Public/ConcertWorkspaceMessages.h
Sent to let the receiver know something is coming. For now only sent from client to server.
[USTRUCT](Programming/UnrealArchitecture/Reference/Structs)() struct FConcertPackageTransmissionStartEvent
FConcertPackage...
PackageInfo
uint64
PackageNumBytes
FGuid
TransmissionId